|“|| Disease gets a bad rap, don't you think? For being filthy. Chaotic. Uh, but, really, that just describes people who get sick. Disease itself... Very...Pure...Single-minded. Bacteria have one purpose --divide and conquer. That's why, in the end...It always wins.
~ The Horseman of Pestilence
Pestilence was one of the Four Horsemen of the Apocalypse and was posing as Dr. Green at a retirement home. He traveled across America spreading swine flu, causing mass outbreaks, while also lording over the demons running a pharmacutical company run by his Right-hand Brady as part of Lucifer's plan to spread the Croatoan virus through swine flu vaccines. Sam and Dean caught up with him, however angry at what they had done to his Siblings, Pestilence betrayed Lucifer to kill the brothers how he was defeated when Castiel cut off his finger that had the ring on it. Without the ring he was no longer able to hold physical form and reduced to a whithered husk.